This invention relates generally to the automatic feeding of electronic components for positioning in a circuit and is particularly directed to the automatic grouping of common electronic components having similar operating characteristics for incorporation in the same circuit in a matched manner.
Individual electronic components are typically positioned and connected in circuit by means of high speed automatic component handling arrangements for more reliable and less expensive electronic circuit fabrication. Component handling arrangements typically include a hopper containing a large number of the same kind of electronic components which are displaced by gravity to an aperture in a lower portion of the hopper for deposit upon either a fixed or a moving component positioning mechanism, whereupon the deposited component is engaged and displaced by a movable robotic gripper assembly for positioning upon a circuit board. In a moving component positioning mechanism the electronic components are typically deposited upon a flexible, tape-like strip in a spaced manner. As the component-carrying strip is unwound from a supply reel, the electronic components are sequentially positioned for grasping by a component engagement and positioning mechanism which positions each component in a given orientation and at a predetermined location on the circuit board. Following removal of a component from the tape-like strip, the strip is wound unto a take-up reel for re-use following the positioning of another set of components thereon.
The length of these component-bearing strips is typically such that a single strip may provide for the transport of several thousand electronic components. All components on a given strip are generally of the same type, i.e., resistors, capacitors, diodes, transistors, etc., with the components on a given strip grouped in accordance with their operating characteristics for certain applications. For example, the specification of a circuit being fabricated may call for the tolerance of a given electronic component used therein to fall within a range of 10.+-.15 representing the allowable range of a given operating parameter of the component. Following manufacture of these components, they are tested and grouped when positioned upon the strip in accordance with the value of this operating parameter as measured during component testing. Thus, those components exhibiting an operating characteristic outside of the aforementioned tolerance range are rejected, while those components having a reading of 6 are grouped together, those components having a reading of 7 are grouped together, and so forth.
In many applications it is not only desirable, but absolutely essential to incorporate identical components having similar operating characteristics in the same circuit. This is commonly referred to as "matching" electronic components in a given circuit to ensure optimum circuit performance. For example, this matching procedure is used in the fabrication of tunable circuits such as used in RF receivers which typically incorporate more than one tuning voltage-responsive component for adjusting the resonant frequency of various stages in the tunable circuit to a desired RF frequency. Generally, the same tuning voltage is applied to each of these tuning voltage-responsive components, such as varactor diodes, in the various stages and it is essential for proper tuning of the circuit that all of these components respond substantially identically to changes in the tuning voltage. Transistors also are frequently used in a matched manner in the same circuit and should ideally exhibit an essentially identical response to a common input control signal.
The present invention provides an arrangement for ensuring that components of the same type grouped in accordance with a given operating characteristic are automatically provided in a matched manner for installation in an electronic circuit. Where the electronic components are provided by means of a moving component supply tape to automatic component engaging and positioning apparatus, the present invention ensures that only those components having common operating characteristics and which are grouped in accordance therewith are incorporated in the same circuit.